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Paraneoplastic syndrome
Paraneoplastic syndromes are diseases or symptoms that are the consequence of a cancer in the body, but are unrelated to the local presence of actual cancer cells. They have one of two major causes: *The release of hormones or cytokines by the tumor cells; and *A response by the immune system to the tumor Paraneoplastic syndromes are more common in older patients, and tend to occur mostly in patients who are middle age and older. They are also more common with certain types of cancer than others. Cancers of the lungs, breasts, ovaries and lymphatic system are more likely to cause such conditions. In some cases, the syndromes caused by a faulty immune system response will present with symptoms before the cancer becomes malignant and starts exibiting it's own symptoms. However, both malignant and benign tumors can have associated paraneoplastic syndromes. Paraneoplastic syndromes are fairly common on House, M.D., occuring in many epiosodes where cancer is the final diagnosis. However, many critics of the series, including the popular medical blog about House Polite Dissent, have noted that paraneoplastic syndromes, which are in any event rare even when a patient has cancer (roughly 1% of cancer patients exhibit such syndromes), are too often used as a way of explaining the patient's symptoms that can't be explained by the underlying cancer. Classification There are four main categories of paraneoplastic syndromes: Endocrine These syndromes are generally caused when a tumor is found in one of the organs that produces hormones starts creating the hormone itself, but can also be caused by tumors elsewhere in the body. Some of the best known of these are: *Cushing's syndrome, which caused uncontrolled weight gain. This can be caused by a tumor that secretes ACTH. It can be caused by small-cell carcinoma, tumor on the pancreas, a tumor on the nerves or a thymoma. *Syndrome of inappropriate antidiuretic hormone secretion or SIADH. This results in low urine volume and a buildup of fluids in the body. It can be caused by small-cell carcinoma or tumors of the central nervous system *Hypercalcemia or high calcium levels. Several cancers can cause this condition, including squamous cell carcinoma of the lungs, breast cancer, kidney cancer, myeloma, cancers of the T-cells and ovarian cancer. *Hypoglycemia or low blood sugar. The most obvious cause is an nesidioblastoma (such as the one in TB or Not TB), but it can also be caused by sarcomas of the connective tissue, bones, fat, bone marrow and other similar tissues, as well as by hepatocellular carcinoma. *Carcinoid syndrome, which causes high levels of serotonin and kallikrein. It can be caused by a bronchial adenoma, pancreatic carcinoma or stomach carcinoma. *Hyperaldosteronism, or an excess of the hormone aldosterone which controls the processing of sodium and potassium in the kidneys. It leads to hypokalemia - low potassium levels. It can be caused by an adenoma of the adrenal gland, Non-Hodgkin's lymphoma, an ovarian carcinoma or cancers of the lung. Neurological These syndromes affect the brain and nervous system. These are generally far more severe than the other types and can be dehabilitating all on their own. They can often persist even after the underlying cancer is treated. They can cause ataxia, dizziness, nystagmus, difficulty swallowing, loss of muscle tone, loss of fine muscle control, slurred speech, memory loss, vision problems, sleep disturbances, dementia, seizures and peripheral neuropathy. these syndromes include: *Lambert-Eaton myasthenic syndrome or LEMS. It is caused when antibodies created to fight the tumor instead attack calcium channels in the muscles. It is usually caused by small-cell carcinoma. *Paraneoplastic cerebellar degeneration. It is caused when the immune system attacks the central nervous system. It is caused by cancers of the lungs, ovaries and breast. *Encephalomyelitis. This can be the result of several conditions, but can also be caused by excess inflammation due to an underlying cancer. *Limbic encephalitis and Brainstem encephalitis. These can be caused by small-cell lung carcinoma. *Paraneoplastic opsoclonus-myoclonus. This is caused when antibodies attack an RNA binding protein called Nova 1. It can be caused by breast carcinoma, ovarian carcinoma, small-cell lung carcinoma and, in children, neuroblastoma *Anti-NMDA receptor encephalitis, caused by an autoimmune reaction to certain types of glutamate receptors. It is usually caused by a teratoma. *Polymyositis. The autoimmune reaction against muscles can be triggered by Non-Hodgkin lymphoma and cancers of the lung and bladder. Mucocutaneous These syndromes affect the skin and the layer where the skin and underlying tissues meet. Unfortunately, most of these can be caused by conditions other than cancer, and in most cases cancer would be a zebra diagnosis for these symptoms. These include *Acanthosis nigricans. Although this can have several underlying causes, the skin discoloration can be caused by carcinomas of the stomach, lungs and uterus which cause the production of a hormone, EGF, which causes uncontrolled cell growth. *Dermatomyositis. This is caused by an immune response that causes inflammation of the skin and underlying tissues. Although it has other causes, it can also be caused by several cancers including those of the breast, ovaries, pancreas, stomach, large intestine and Non-Hodgkin's lymphoma. *Leser-Trelat sign, a series of dark spots underneath the surface of the skin resembling liver spots. These are often a sign of colon cancer. *Necrolytic migratory erythema, a red blistering rash that usually appears on the abdomen. It is usually caused by a glucagonoma, a glucagon producing tumor. *Sweet's syndrome or febrile neutorphilic dermatosis, characterized by a certain type of papule. These can be caused by blood cancers such as leukemia. *Florid cutaneous papillomatosis, a sudden appearance of multiple papillomas that look like warts. These can be caused by many types of cancer, but are most commonly associated with stomach carcinomas. *Pyoderma gangrenosum, a type of necrosis that leads to large skin ulcers. These can be caused by multiple myeloma. *Acquired generalized hypertrichosis, where the body grows an unusually large amount of hair. Although hypertricosis has many causes, it can be caused by several different types of cancer. Hematological These syndromes affect the blood. Almost any general blood condition can be caused by an underlying cancer. These syndromes include: *Granulocytosis, from an excess production of the hormone that encourages blood production. This syndrome is common with leukemia *Polycythemia, from the excess production of erythropoietin. It can be caused by cancers of the kidneys, brain and liver. *Trousseau sign, characterized by tender nodules in the veins which characterize clotting . It is characteristic of cancers of the pancreas and lungs. *Nonbacterial thrombotic endocarditis, where vegetations grow on the heart valves due to the blood being very succeptible to clotting. This can happen with any cancer, but is more likely with cancers of the pancreas. It usually only appears in very advanced stages of cancer. *Anemia. Although anemia can be caused by many conditions, it is also possible with neoplasms of the thymus gland. Other Some syndromes do not fit neatly into any of the main categories. These include: *Membranous glomerulonephritis, a progressive disease of the kidneys. It can be caused by a tumor in the lungs or large intestine, although the vast majority of cases are ideopathic. *Tumor-induced osteomalacia. This condition causes the kidneys to excrete phosphates at a higher than normal rate, leading to weaknesses in the bones. It is often caused by benign tumors in the connective tissues. *Stauffer syndrome, liver dysfunction usally caused by a tumor in a kidney, and more rarely by other malignancies. *Neoplastic fever, a fever attributable to an underlying cancer On the series Although cancer is by far the most common diagnosis on the series, in many of those cases, the actual symptoms being suffered by the patient were attributed to paraneoplastic syndrome and not the underlying cancer. However, as has been noted, this storytelling device often starts lumping a zebra onto another zebra. Most paraneoplastic syndromes are associated with one or a few cancers, and most cancers are associated with one or a few paraneoplastic syndromes. Although it is theoretically possible that any of the paraneoplastic syndromes can be triggered by any type of cancer, on the series this is usually not a good fit. The Mom To Be In Babies & Bathwater, Naomi Randolph suffered from fainting, impaired function of the liver and kidneys, increased levels of BUN and creatinine, cramps, difficulty swallowing, myasthenia and one drooping eyelid. After quickly ruling out that her pregnancy was responsible for her symptoms, they found a granuloma on her lung indicating small-cell carcinoma. The doctors told her that her other symptoms were the result of Lambert-Eaton myasthenic syndrome. This is a plausible diagnosis. Lambert-Eaton does cause muscle weakness, and small-cell lung carcinoma is the most common cause. Lambert-Eaton also causes double vision, drooping of the eyelids and difficulty swallowing. Although the usual way of confirming Lambert-Eaton is electromyography, the existence of the granuloma most likely made the test unnecessary given her other symptoms. In addition, the doctor's recommendation to immediately treat the underlying cancer was probably her best treatment option to eliminate the paraneoplastic syndrome. The Teenage Supermodel In Skin Deep, Alex was suffering from double vision, catoplexy, sudden agressive behavior, nausea, twitching, short term memory loss and elevated protein levels in her CSF. Her symptoms were attributed to paraneoplastic syndrome which was eventually traced to testicular cancer. Apart from the unlikely combination of paraneoplastic syndrome and testicular cancer in a person with male pseudohermaphroditism, this one is actually plausible. The most common paraneoplastic sydrome associated with testicular cancer is limibc encephalitis, which causes short term memory deficit, headaches, irritablility, sleep disturbance, delusions, hallucinations, agitation, seizures and psychosis. No treatment is sure-fire, but House's choice of intravenous immunoglobulin is the usual course of action. In addition, the syndrome can also be caused by ovarian cancer, so House was right to ensure that Wilson had checked for it. House's diagnosis of paraneoplastic syndrome was a bit of a stretch, however. It was essentially just a guess that turned out right. Paraneoplastic limbic encephalitis can only be confirmed with test of antibodies found in the CSF. The Homeless Patient In Histories, Victoria was suffering from numbness, photophobia, disorientation, paranoia, ineffectiveness of sedatives and hydrophobia. She was thought to be suffering from paraneoplastic syndrome which was eventually traced to Rabies. ( Summary Incomplete.) 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